"I have super thick, light-brown hair with blonde highlights and masking has become an obligatory part of my hair-care routine. I usually mask once a week and when I do so, I skip out on my normal conditioner entirely in place of a hydrating, restoring formula. One that I've been loving recently is the Kérastase Masque Ultra-Violet Purple Hair Mask for Blonde Hair ($59). It leaves my hair feeling soft, smooth and keeps my blonde highlights looking luminous and healthy." — Marisa Petrarca, associate editor, Makeup.com